Originally Posted by pallen

Some of it is good. A lot of it is not. The rotational injury stuff is pretty weak, based on "some doctors think". Sure, its worth looking into, but it pretty weak right now. The whole population stuff deals with helmet laws being introduced. Its very difficult to draw any solid conclusion from these - there are a lot of factors at work there. The less exercise and people being more risky with helmets is irrelevant. The answer to those is not to stop wearing helmets, but to get out and ride and don't be stupid just because you're wearing a helmet.

I would be curious if anyone has published any crash test data with and without helmets. The only way to really know if helmets are effective is to try to simulate typical bike crashes with a test dummy fitted with sensors. I realize this is pretty difficult to pull off, but I'm sure it can be done. Look at the same kind of crash 100 times and compare the sensor data from a helmeted head and a non helmeted head. Of course a dummy doesnt have the curl up instincts and such that a human has, but I still think that would be the best way to know exactly how much impact a helmet can absorb.